Polyclad Genus Pseudoceros — Hyman 
221 
November 5, 1944, under pieces of coral rock 
exposed by the tide at Mios Woendi, Padaido 
Island, near Biak, Dutch New Guinea. 
This is a relatively small species, varying in 
length from 15 to 25 millimeters. The body 
is of elongate oval form (Fig. la), with the 
usual pair of tentacular folds at the anterior 
margin, bearing eyes as shown in Figure lb. 
Shortly behind the tentacular folds in the 
middorsal line are found the two small clust- 
ers of cerebral eyes over the brain region. The 
color is stated by the collector to have been 
orange with a bright blue border l/l6-inch 
wide. No trace whatever of this color remains 
in the preserved specimens. Cleared whole 
mounts show the typical features of the genus, 
in addition to the tentacular folds (Fig. la). 
There is a short but broad, highly ruffled 
pharynx, consisting of a few greatly folded 
lateral branches. Immediately behind the phar- 
ynx is seen the single male apparatus and 
behind this the female gonopore surrounded 
by the usual radiating cement glands. The 
relative positions of male and female gono- 
pores and of the sucker appear in Figure la. 
Behind the female gonopore the main intes- 
tine extends posteriorly, ending blindly some 
distance anterior to the posterior margin and 
giving off along its course numerous side 
branches that anastomose at once into a fine- 
meshed network as typical of the genus. Only 
the proximal meshes are drawn in Figure la. 
Along each side of the main intestine courses 
a uterus filled with eggs. 
All the specimens are sexually mature. In 
view of the difficulties of species identifica- 
tion in the genus, the sexual region of one 
specimen was sectioned and a sagittal view 
of the copulatory apparatuses is given in Fig- 
ure Ic. The expanded sperm ducts unite to a 
short, common sperm duct that enters the 
rear end of the male apparatus, consisting of 
a long tubular seminal vesicle with thick mus- 
cular wall of circular fibers, and a small oval 
prostatic vesicle. The ducts of these two vesi- 
cles enter the small penis papilla within which 
they unite. The penis papilla bears the usual 
stylet surrounded by a penis sheath, and pa- 
pilla and sheath lie in the inner end of a 
somewhat extensive and irregularly formed 
male antrum that opens below by the male 
gonopore. The female gonopore leads into a 
vertical tubular female antrum that opens into 
the short, laterally expanded cement pouch; 
this receives on all sides the usual masses of 
cement glands. From the cement pouch the 
vagina continues dorsally with a backward 
curve and soon receives the two uteri. All of 
the features of the copulatory apparatuses are 
typical of the genus but the details should 
serve to distinguish this species from others 
of similar coloration. The most distinctive 
feature of the copulatory apparatuses is the 
long, tubular, and thick-walled seminal vesi- 
cle, contrasting with the relatively small 
prostatic vesicle. 
Unfortunately, none of the preceding de- 
scriptions assigned to P. concinmis give any 
details of the sexual anatomy, and as the 
statements about the color are somewhat dis- 
crepant I am not able to identify my spec- 
imens with certainty as P. concinnus. In the 
original description the length is given as 
15 millimeters, hence averaging less than the 
present specimens, and the color is described 
as cream, approaching yellow, with a blue 
border composed of contiguous spots, and a 
narrow middorsal blue streak. The type local- 
ity is Labuan Island, off Borneo. 
Lang (1884: 593) merely repeated the orig- 
inal description of Proceros concinnus without 
offering any opinion as to its systematic po- 
sition. Laidlaw (1903: 315) reported several 
specimens obtained from the Straits of Ma- 
lacca that were "colored exactly like Proceros 
concinnus Coll., viz., they are blue, with orange 
margin and median stripe"! This is either a 
slip of the pen in reverse or, more likely, the 
coloration actually was the reverse of that of 
Collingwood’s species. As Laidlaw’s speci- 
mens were also very small, 8 to 10 millimeters 
in length, it appears certain that they were 
not P. concinnus. The surmise of Laidlaw, 
accepted later by Kaburaki (1923: 643), that 
